Document CH-654 599 makes known an embodiment of a circular comb for a comber, wherein a part 27 (called a guide element) is installed following a comb clothing (a needle segment having comb needles) in order to narrow the gap between the circular comb and the lower nipper plate. In this connection, the circular comb is rotatably mounted within a suction channel, to which a vacuum is applied in order to suction out the extracted components. The purpose of the additionally installed guide element (part 27) is to prevent the end of the fibrous web, which has been fed back by the detaching rollers, from being lifted off the lower detaching roller by the suction airflow present in the suction channel before the piecing process takes place. Such a lifting of the end of the fibrous web before the joining of the extracted fiber tuft protruding from the nipper disrupts the downstream joining process (piecing process) and results in unclean and faulty splices (piecings). The solution proposed in CH-654 599 improves the previous embodiments in terms of disruptive suction airflows.
As is also found in the cited prior art, the additional guide element (part 27) can extend only around a certain rotation angle of the circular comb in order to prevent a collision with the lower nipper plate of the nipper unit, which pivots back and forth.
Due to the demand to operate the combers at continuously increasing nip rates, the requirements regarding the production of high quality piecings are also continuously increasing. That is, at high nip rates, unwanted airflows have an even greater effect on the piecing process. In addition, it is becoming increasingly difficult to hold the fed-back end of the fibrous web on the periphery of the lower detaching roller before the end of the extracted fiber tuft protruding from the nipper is placed onto the end of the fibrous web. Due to the higher rotational speeds of the rotating parts, such as the circular comb and the brush roller, and the faster movements of the remaining parts, such as, e.g., the nipper unit, the generated airflows also change in the region of the join between the nipper unit and the detaching rollers. That is, the known guide elements following the comb unit, in the current geometric shape, are no longer capable of controlling the airflows in the region of the join such that a non-disrupted joining (piecing) of the extracted fiber tuft end to the fed-back end of the fibrous web is ensured.